m = size(Xtest, 1);
p = 8;

X_poly = polyFeatures(Xtest, p);
[X_poly, mu, sigma] = featureNormalize(X_poly);  % Normalize
X_poly = [ones(m, 1), X_poly];                   % Add Ones

testError = linearRegCostFunction(Xtest, ytest, theta, 3)
